title: Cafeteria diet-induced sleep is blocked by subdiaphragmatic vagotomy in rats.
abstract: Feeding rats a cafeteria diet results in increased food intake and excess sleep. Furthermore, vagal afferent activity is altered by a variety of gastrointestinal factors, and vagal stimulation can induce sleep. We investigated, therefore, the hypothesis that the vagal nerve plays a critical role in mediating the sleep-inducing effects of cafeteria feeding. We examined the effects of a cafeteria diet on sleep, electroencephalographic (EEG) slow-wave activity (SWA), and brain temperature (Tbr) in control and vagotomized rats. EEG, electromyogram, and Tbr were recorded for 7 consecutive days. Day 1 was considered a baseline day; normal rat chow was available ad libitum. On days 2-4, the animals were fed, in addition to normal chow, a mixed, energy-rich diet (cafeteria diet). On days 5-7, the rats were again fed only normal rat chow. In control rats, the cafeteria diet resulted in an increase in non-rapid eye movement sleep (NREMS), which was the result of a significant lengthening of the NREMS episodes. In contrast, feeding vagotomized rats the cafeteria diet resulted in a decrease in NREMS. Cafeteria feeding decreased REMS and EEG SWA and increased Tbr in both control and vagotomized rats. These results suggest that an intact vagus plays a key role in the NREMS-inducing effects of the cafeteria diet.
authors.affiliation: Department of Physiology and Biophysics, University of Tennessee, Memphis 38163, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Hansen
authors.forename: L
authors.initials: L
authors.lastname: Kapás
authors.forename: J
authors.initials: J
authors.lastname: Fang
authors.forename: J M
authors.initials: JM
authors.lastname: Krueger
mesh_terms: D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001833:Body Temperature Regulation; D001921:Brain / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D003624:Darkness; D003964:Diaphragm; D004032:Diet; D004569:Electroencephalography; D005522:Food Services; D006801:Humans; D008027:Light; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages; D012895:Sleep, REM; D014628:Vagotomy